Anatomy and Kinesiology
This domain tests structure–function reasoning: whether you can move from a joint's shape, axis and innervation to the exercise or manual technique you would actually choose. Items typically present a movement, a muscle action, or a nerve lesion and ask for the mechanical or anatomical explanation.
Planes, axes and joint motion
- Sagittal plane around a frontal (coronal) axis: flexion and extension.
- Frontal plane around a sagittal axis: abduction, adduction, lateral flexion.
- Transverse plane around a vertical axis: rotation, pronation/supination, horizontal abduction.
- Osteokinematics is the visible bone movement; arthrokinematics is what happens at the joint surfaces (roll, glide, spin).
The convex–concave rule
When the moving surface is convex on a fixed concave partner, roll and glide are in opposite directions. When the moving surface is concave on a fixed convex partner, roll and glide are in the same direction. This rule decides the direction of the accessory glide you mobilise.
Muscle roles and levers
- Prime mover, antagonist, synergist (true or neutralising), and fixator/stabiliser.
- Active insufficiency: a shortened two-joint muscle cannot produce force. Passive insufficiency: a lengthened two-joint muscle limits range. Classic two-joint muscles are rectus femoris, hamstrings, gastrocnemius, biceps brachii and flexor digitorum profundus.
- Third-class levers dominate the limbs (effort between fulcrum and load), favouring speed and range over force; second-class is the calf raise; first-class is the nodding head at the atlanto-occipital joint.
Segmental and peripheral nerve anchors
Deltoid C5 axillary; biceps C5–C6 musculocutaneous; elbow extensors C7 radial; wrist extensors C6–C7 radial; finger flexors C8 median/ulnar; quadriceps L3–L4 femoral; tibialis anterior L4–L5 deep fibular; gastrocnemius S1–S2 tibial; peroneals L5 superficial fibular.
Worked example
A patient cannot abduct the shoulder past 90° and you plan an inferior glide. Reasoning: at the glenohumeral joint the humeral head is convex and the glenoid concave, so during abduction the head rolls superiorly while gliding inferiorly. A grade III inferior glide restores the missing arthrokinematic component. Above roughly 120°, scapular upward rotation and posterior tilt must contribute; scapular movement exceeding humeral movement (a reversed rhythm) points to shoulder dysfunction rather than a pure capsular restriction.
Traps that cost marks
- Reversing the convex–concave rule under time pressure.
- Confusing close-packed (maximum congruence, ligaments taut, accessory motion absent) with loose-packed (resting position, accessory motion available).
- Quoting a peripheral nerve when the question asks for a nerve root level, or vice versa.